Generics have been used on an auto trait.
Erroneous code example:
#![feature(auto_traits)]
auto trait Generic<T> {} // error!
RunSince an auto trait is implemented on all existing types, the compiler would not be able to infer the types of the trait’s generic parameters.
To fix this issue, just remove the generics:
#![feature(auto_traits)]
auto trait Generic {} // ok!
Run